Zinc-tin oxide thin-film transistors

ABSTRACT

Methods of forming transparent zinc-tin oxide structures are described. Devices that include transparent zinc-tin oxide structures as at least one of a channel layer in a transistor or a transparent film disposed over an electrical device that is at a substrate.

TECHNICAL FIELD

This disclosure relates generally to conductive oxide films.

BACKGROUND

Transparent conducting oxides (TCOs) are used in electronic structureswhere both electrical conduction and optical transparency are required.Some example electronic structures include liquid crystal displays(LCDs), light-emitting diodes (LEDs), solar cells, and others. Zinc tinoxide (ZTO) is used because of high transparency and low resistivity,among other reasons.

Technical challenges exist between scaling down, also known asminiaturization, and acceptable function of a thin-film TCO.

What are needed are methods to form better TCOs that can address thesechallenges. What are also needed are improved TCO structures that canalso address these challenges.

BRIEF DESCRIPTION OF THE DRAWINGS

The previously mentioned issues are addressed by the present disclosureand will be understood by reading and studying the followingspecification, of which the figures are a part.

FIG. 1A shows a cross-section elevation of a semiconductor device duringprocessing according to an embodiment;

FIG. 1B shows a cross-section elevation of the semiconductor devicedepicted in FIG. 1A after further processing according to an embodiment;

FIG. 2A shows a cross-section elevation of a semiconductor device duringprocessing according to an embodiment;

FIG. 2B shows a cross-section elevation of the semiconductor devicedepicted in FIG. 2A after further processing according to an embodiment;

FIG. 2C shows a cross-section elevation of the semiconductor devicedepicted in FIG. 2B after further processing according to an embodiment;

FIG. 2D shows a cross-section elevation of the semiconductor devicedepicted in FIG. 2C after further processing according to an embodiment;

FIG. 3 shows a cross-section elevation of a semiconductor deviceaccording to an embodiment;

FIG. 4 shows a flow diagram of an example method of forming a zinc-tinoxide thin-film transistor according to an embodiment;

FIG. 5 shows a material deposition system according to an embodiment ofthe invention;

FIG. 6 shows a block diagram of an electronic device according to anembodiment of the invention; and

FIG. 7 shows a block diagram of an electronic device according to anembodiment of the invention.

DETAILED DESCRIPTION

The embodiments of a device, an apparatus, or an article describedherein can be manufactured, used, or shipped in a number of positionsand orientations.

FIG. 1A is a cross-section elevation of an electrical device 100 thatincludes a substrate 110 and a surface 112 such as a semiconductor baseddevice. The surface 112 includes variations in surface topology asillustrated by the feature 114, such as a trench. Although the trench114 is illustrated as an example, other variations in topology, bothabove and below the surface 112, are useful to describe embodiments.

An electronic device 116 is also shown in block diagram form in FIG. 1Aas being disposed in the substrate 110. In an embodiment, the electronicdevice 116 is disposed on the surface 112 of the substrate 110. In anyevent, the electronic device 116 is disposed at the substrate. Examplesof electronic devices 116 include optical electronic devices such asactive pixel sensors, photovoltaic devices, light emitting diode (LED)devices, plasma display screen devices etc. Other electronic devices 116that benefit from adjacent structures with optical transparency arewithin the scope of the disclosed embodiments.

Other electronic devices can be formed upon the surface 112, such as anepitaxial channel film for a semiconductive transistor.

FIG. 1B is a cross-sectional elevation of the electrical device depictedin FIG. 1A after further processing. The electrical device 101 has beenprocessed with a conformal transparent conducting oxide (TCO) film 118including zinc and tin over the surface 112. In an embodiment, the TCOfilm 118 includes a zinc-doped tin oxide film that is formed by atomiclayer deposition (ALD) as set forth in this disclosure. In anembodiment, the TCO film 118 includes a tin-doped zinc oxide film thatwas formed by ALD. In an embodiment, the TCO film 118 includes azinc-tin oxide film that was formed by ALD.

In an embodiment, a first reactant film of ZnO is formed, followed by asecond reactant film of a tin-bearing material. Annealing is used toform a ZnSn TCO film 118. In an embodiment, a first reactant film of SnOis formed, followed by a second reactant film of a zinc-bearingmaterial. Annealing is used to form a ZnSn TCO film 118. In anembodiment, a first reactant film of ZnO is formed, followed by a secondreactant film of a tin dielectric compound. Annealing is used to form aZnSn TCO film 118. In an embodiment, a first reactant film of SnO isformed, followed by a second reactant film of a zinc dielectriccompound. Annealing is used to form a ZnSn TCO film 118. In any of theseembodiments, the first reactant film can be a chemisorbed tin-orzinc-containing organometallic film monolayer, and the second reactantfilm can be the other zinc- or tin-containing dielectric that isself-limited in reacting with the chemisorbed first reactant film.

As discussed above, an ALD-formed zinc-tin oxide film provides a numberof useful properties over other transparent conducting oxides. Zinc-tincompounds of films provide high carrier mobility, low resistivity, andhigh transparency among other qualities. Highly mobile carriers areuseful because they can be formed in low concentrations to achieve agiven electrical resistivity. Low concentrations of carriers in turnprovide less optical absorption across many wavelengths. The TCO film118 is depicted forming a conformal layer over a challenging topologysuch as the trench 114. The TCO film 118 is also shown covering at leasta portion of the electronic device 116.

By use of ALD methods, there are several precursor chemistries that canbe used to achieve ALD-formed transparent zinc-tin oxides according tothe several disclosed embodiments. Monolayers that contain zinc or tincan be formed, for example, by using at least one of zinc chloride andtin chloride, as well as water as reactants. In an example, aself-limiting growth of a zinc chloride first reactant film is formed byALD, followed by purging the environment of the substrate and thereafterfollowed by adsorbing a tin chloride second reactant film upon the zincchloride first reactant film. Thereafter, processing occurs in atemperature range from about 400° C. to about 500° C. In an exampleembodiment, a polycrystalline zinc-tin oxide film is formed. Otherchemistries and methods are set forth herein. For example, althoughchlorides of zinc and tin are set forth, either or both of the films maybe referred as halide films.

FIG. 1B illustrates an incoming beam 120 of electromagnetic energy suchas visible frequency light, ultraviolet (UV) light, infrared light, orother spectra. Selected devices within the scope of the disclosedembodiments include devices such as solar cells, gas sensor components,active pixel sensors, and others that benefit from the ability toreceive the incoming beam 120 through a TCO film 118. FIG. 1B alsoillustrates an outgoing beam 122. Selected devices within the scope ofthe disclosed embodiments likewise include devices such as lightemitting diodes, plasma display screen emitters, and others that benefitfrom the ability to transmit an outgoing beam through the disclosedembodiments and their equivalents of a TCO film 118. One use of TCOs inconjunction with devices such as these includes interconnectioncircuitry between devices, to an edge of an array or a chip, to a powersupply, etc. Another use of TCOs in conjunction with devices such asthese includes conducting layer components of devices themselves, suchas a channel layer for a field-effect transistor (FET).

The TCO film 118 is formed using monolayer deposition methods asdescribed in embodiments below. Methods include ALD techniques,chemically self-limiting techniques such as the second reactant islimited with combination with the first reactant. Other techniques thatform monolayers with controlled thickness can also be used, such ascontrolled-atmosphere ALD. As defined above, the term monolayer definesa layer that is substantially one molecule or one atom thick. Althoughsubstantially one layer thick, some variation on the order of zero totwo molecules is within the scope of the disclosed embodiments.

The methods described form a unique structure compared to otherdeposition methods. Selected monolayer processing methods can provide asubstantially amorphous TCO structure that is not possible using otherdeposition techniques. Other processing variations provide a finecrystal distribution such as a nanocrystalline TCO structure.Micro-scale and nano-scale crystal structures provide unique physicalproperties such as highly durable films.

FIG. 2A shows a cross-section elevation of a semiconductor device 200during processing according to an embodiment. A substrate 210 includinga dielectric base 212 is provided, such as a low-dielectric constant(low-k) dielectric. In an embodiment, the dielectric base 212 is apolyimide material. A semiconductor materials section 214 includes aburied dielectric layer 216 such as a buried oxide that has been formedin monocrystalline silicon by ion implantation. The semiconductormaterials section 214 also includes an active section 218 such asvendor-doped monocrystalline silicon, to give the semiconductormaterials section 214 either a P-type doping or an N-type dopingaccording to an embodiment.

FIG. 2B shows a cross-section elevation of the semiconductor devicedepicted in FIG. 2A after further processing according to an embodiment.In a processing embodiment, the semiconductor device 201 exhibits aplurality of chemically adhered monolayers that is formed above thesemiconductor materials section 214. A first monolayer 222 has beenformed above and on the semiconductor materials section 214. In anembodiment, an ALD process is carried out such that the first monolayer222, which contains an organometallic molecule, has been chemisorbedonto the semiconductor materials section 214. Thereafter, a subsequentmonolayer 224 has been formed above the first monolayer 222.

FIG. 2C shows a cross-section elevation of the semiconductor devicedepicted in FIG. 2B after further processing according to an embodiment.The semiconductor device 202 exhibits an alloyed result of the pluralityof monolayers. In an example embodiment, a zinc-tin TCO film 226 isformed from monolayer precursors into the zinc-tin TCO film 226.

In another example embodiment, an organo-zinc first monolayer (e.g.first monolayer 222 in FIG. 2B) is formed by ALD. Amethylcyclopentadinyl trimethylzinc (MeCpZnMe₃) composition is flowedinto a microelectronic device processing tool along with oxygen and at atemperature of about 300° C. The first monolayer 222, which containszinc in this embodiment, is allowed to chemisorb onto the semiconductormaterials section 214. The process can require about four seconds (s)and the first monolayer 222 is observed to be about 0.45 {acute over(Å)}ngstrom ({acute over (Å)}) in thickness.

Thereafter, the processing tool is purged of the MeCpZnMe₃ with anon-reactive gas and an organo-tin subsequent monolayer (e.g. secondmonolayer 224 in FIG. 2B) is formed above and on the first monolayer222. A homoleptic N,N″-dialkylactamidinato tin compound is used in thepresence of molecular hydrogen gas.

The plurality of two monolayers 222 and 224, are reacted under alloyingconditions to form the TCO film 226. The amount of chemisorbed zincfirst monolayer 222 can limit the alloying effect.

In an embodiment, the first-reactant and second-reactant precursorlayers are formed by multiple alternating ALD repetitions, and thethickness of the TCO film 226 is about 3 {acute over (Å)}. In anembodiment, the thickness of the TCO film 226 is in a range from about 3{acute over (Å)} to about 300 {acute over (Å)}. In an embodiment, thethickness of the TCO film 226 is in a range from about 10 {acute over(Å)} to about 50 {acute over (Å)}.

In an embodiment where the composition of the TCO film 226 impartssemiconductive characteristics, the TCO film 226 can be referred to asan epitaxial, transparent semiconductive oxide (TSO) film 226 because ithas been formed directly upon the semiconductor materials section 214.In an embodiment, where the composition of the TCO film 226 impartssemiconductive characteristics, the TCO film 226 can be referred to asmerely a TSO film 226, where it has not been formed upon asemiconductive section such as upon a dielectric material. Hereinafterfor simplicity, the TCO and the TSO embodiments will be referred togenerically as “TCO” unless specifically referred to otherwise.

FIG. 2D shows a cross-section elevation of the semiconductor devicedepicted in FIG. 2C after further processing according to an embodiment.The semiconductor device 203 has been further processed by forming agate stack. A gate oxide film 228 is disposed upon the TSO film 226, anda control gate film 230 is formed upon the gate oxide film 228. Further,a dielectric cap film 232 is formed upon the control gate film 230, anda spacer 234 acts to insulate the control gate film 228.

In an embodiment, the gate oxide film 228 is also formed by ALD suchthat the thickness of the gate oxide film 228 is less than the thicknessof the control gate film 230. In an embodiment, the gate oxide film 228is an oxide such as a silicon oxide. The control gate film 230 can bemade from a metal or metal alloy according to an embodiment. In anembodiment, the control gate film 230 is an ALD-formed film, made by thechemisoption of a metal or metal alloy precursor.

FIG. 2D also indicates further processing to form self-alignedsource/drain (S/D) regions in the TCO film 226. Further processing, suchas forming the spacer dielectrics on the gate stack and bit-lineconnections to the TCO film 226 can be carried out according toconventional technique. The S/D regions are alternatively shown as beingalso formed in the active section 218.

FIG. 3 shows a cross-section elevation of a semiconductor device 300according to an embodiment. A substrate 310 including a dielectric base312 is provided, such as a low-k dielectric. In an embodiment, thedielectric base 312 is a polyimide material. A semiconductor materialssection 314 includes a dielectric layer 316, such as an oxide that hasbeen formed in monocrystalline silicon by ion implantation.

The semiconductor device 300 also exhibits an alloyed result of theplurality of monolayers in the semiconductor materials section 314. Inan example embodiment, a zinc-tin TCO film 326 is formed from monolayerprecursors to achieve the zinc-tin TCO film 326.

In an embodiment the zinc-tin TCO film 326 is in a thickness range fromabout 3 {acute over (Å)} to about 300 {acute over (Å)}. In anembodiment, the thickness of the TCO film 326 is in a range from about10 {acute over (Å)} to about 50 {acute over (Å)}.

In this embodiment, the composition of the TCO film 226 hassemiconductive characteristics; the TSO film 326 can be referred to aschannel TSO film 326 because it has acts as a channel film for afield-effect transistor.

A gate oxide film 328 is disposed upon the TSO film 326 and a controlgate film 330 is formed upon the gate oxide film 328. Further, adielectric cap film 332 is formed upon the control gate film 328, and aspacer 334 acts to insulate the control gate film 328.

In an embodiment, the gate oxide film 328 is also formed by ALD suchthat the thickness of the gate oxide film 328 is less than the thicknessof the control gate film 330. In an embodiment, the gate oxide film 328is an oxide such as a silicon oxide. In an embodiment, the gate “oxide”film is more generically referred to as a gate dielectric film 328, asthe film is not limited to oxides. The control gate film 330 can be madefrom a metal or metal alloy according to an embodiment. In anembodiment, the control gate film 330 is an ALD-formed film, made by thechemisoption of a metal or metal alloy precursor. FIG. 3 also indicatesself-aligned S/D regions in the TSO film 326. Further processing, suchas forming bit-line connections to the TSO film 326 can be carried outaccording to conventional technique.

In an embodiment, processing can be done that results in both a TCO filmthat abuts an electronic device such as the TCO film 118 and electronicdevice 116 depicted in FIG. 1B, and a TSO film as part of an FET, suchas the gate stack depicted in FIG. 3 with the TSO film 326 acting as thechannel layer.

The methods described form a unique structure compared to otherdeposition methods. Using monolayer deposition methods, a TCO film or aTSO film can be formed with step coverage over surface topology that issuperior to other deposition techniques. Other processing variationsprovide a fine crystal distribution such as a nanocrystalline TCO filmor TSO film.

FIG. 4 shows a flow diagram of an example method of forming a zinc-tinoxide thin-film transistor according to an embodiment. In process 410, amonolayer that includes a first TCO film or TSO film precursor isdeposited. In an embodiment, the first monolayer is zinc that ischemisorbed.

At 412, a purge of the processing tool is carried out that leaves thefirst monolayer chemisorbed.

At 420, the process includes forming a subsequent monolayer above thefirst monolayer. In an embodiment, a tin subsequent monolayer is formedabove and on the zinc first monolayer.

At 430 the plurality of monolayers is processed to form a TCO film orTSO film. In the processing embodiment, mixing includes processes suchas annealing or diffusion mixing of the various monolayer precursors. Inthe processing embodiments, the organic materials that carry theselected metals are driven off by either decomposition orvolatilization.

At 440 the process includes forming the film into a TSO film. In anembodiment, the TSO film acts as a channel layer in a field-effecttransistor. In an embodiment, the TCO film acts as a window throughwhich an electronic device sends or receives radiant energy, such at theelectronic device 116 shown in block diagram form in FIG. 1A. An exampleembodiment of an electronic device includes optical electronic devices.In an example embodiment, the electronic device is an active pixelsensor. In an example embodiment, the electronic device is aphotovoltaic device. In an example embodiment, the electronic device isan LED. In an example embodiment, the electronic device is a plasmadisplay screen device. Other light-transmitting or receiving devices arealso useful for abutting a TCO film embodiment as set forth in thisdisclosure.

FIG. 5 shows an embodiment of an ALD system 500 for processing aplurality of monolayers into a TCO film or TSO film according to theteachings of the present invention. The elements depicted are thoseelements necessary for discussion of the present invention such thatthose skilled in the art may practice the present invention withoutundue experimentation. Processing variable such as temperature andpressure, duration, etc. are chosen to reach a desired structuremorphology.

In ALD, gaseous precursors are introduced one at a time to the substratesurface mounted within a reaction chamber (or tool). This introductionof the gaseous precursors takes the form of pulses of each gaseousprecursor. Between the pulses, the reaction chamber is purged with agas, which in many cases is an inert gas, or is evacuated.

In a chemisorption-saturated ALD (CS-ALD) process, during the firstpulsing phase, reaction with the substrate occurs with the precursorsaturatively chemisorbed at the substrate surface. Subsequent pulsingwith a purging gas removes precursor excess from the reaction chamber.

The second pulsing phase introduces another precursor on the substratewhere the growth reaction of the desired film takes place. Subsequent tothe film growth reaction, reaction byproducts and precursor excess arepurged from the reaction chamber. With favorable precursor chemistrywhere the precursors adsorb and react with each other on the substrateaggressively, one ALD cycle can be preformed in less than one second inproperly designed flow type reaction chambers. Typically, precursorpulse times range from about 0.5 sec to about two to three seconds.

In ALD, the saturation of all the reaction and purging phases makes thegrowth self-limiting. This self-limiting growth results in large areauniformity and conformality, which has important applications forapplications such as planar substrates, deep trenches, and in materialdeposition on porous materials, other high surface area materials,powders, etc. Examples include, but are not limited to organometallicTCO film precursors. Significantly, ALD provides for controllingdeposition thickness in a straightforward, simple manner by controllingthe number of growth cycles. Consequently, a laminate can be formed suchthat although the first monolayer may be one or two elements of metalthick, a laminate can be formed to achieve thicker TCO structures. In anembodiment, a two-component, e.g., a zinc-tin oxide film is formed, butthe zinc-tin oxide film is made from at least three monolayers, one ofwhich is an oxygen-bearing film. In any event, a tin-zinc oxide solidsolution is formed such as the zinc-tin TCO film 226 depicted in FIG.2D.

The precursors used in an ALD process may be gaseous, liquid, or solid.Typically, liquid or solid precursors are volatile. The vapor pressuremust be high enough for effective mass transportation. Also, solid andsome liquid precursors are heated inside the reaction chamber andintroduced through heated tubes to the substrates. The sufficient vaporpressure is reached at a temperature below the substrate temperature toavoid the condensation of the precursors on the substrate. Due to theself-limiting growth mechanisms of ALD, relatively low vapor pressuresolid precursors can be used though evaporation rates may somewhat varyduring the process because of changes in their surface area.

There are several other considerations for precursors used in ALD.Thermal stability of precursors at the substrate temperature is a factorbecause precursor decomposition affects the surface control. ALD isheavily dependent upon the reaction of the precursor at the substratesurface. A slight decomposition, if slow compared to the ALD growth, canbe tolerated.

The precursors chemisorb on or react with the surface, though theinteraction between the precursor and the surface as well as themechanism for the adsorption is different for different precursors. Themolecules at the substrate surface react aggressively with the secondprecursor to form the desired solid film. Additionally, precursorsshould not react with the film to cause etching, and precursors shouldnot dissolve in the film. Using highly reactive precursors in ALDcontrasts with the selection of precursors for conventional CVD.

The by-products in the reaction are typically gaseous to allow theireasy removal from the reaction chamber. Further, the by-products shouldnot react or adsorb on the surface.

In a reaction sequence ALD (RS-ALD) process, the self-limiting processsequence involves sequential surface chemical reactions. RS-ALD relieson chemistry between a reactive surface and a reactive molecularprecursor. In an RS-ALD process, molecular precursors are pulsed intothe ALD reaction chamber separately. The metal precursor reaction at thesubstrate is typically followed by an inert gas pulse or chamberevacuation to remove excess precursor and by-products from the reactionchamber prior to pulsing the next precursor of the fabrication sequence.

Using RS-ALD, films can be layered in equal metered sequences that areessentially identical in chemical kinetics, deposition per cycle,composition, and thickness. RS-ALD sequences generally deposit less thana full layer per cycle. Typically, a deposition or growth rate of about0.25 to about 2.00 {acute over (Å)} per RS-ALD cycle can be realized.

RS-ALD provides in these embodiments for use of low temperature andoxidizing processes, for growth thickness dependent solely on the numberof cycles performed, and an ability to engineer multilayer laminatefilms with resolution of one to two monolayers.

RS-ALD processes provide for robust deposition of films or otherstructures. Due to the unique self-limiting surface reaction materialsthat are deposited using RS-ALD, such films are free from processingchallenges such as first wafer effects and chamber dependence.Accordingly, RS-ALD processes are easy to transfer from development toproduction and from 200 to 300 mm wafer sizes in production lines.Thickness depends solely on the number of cycles. Thickness cantherefore be tightly configured by controlling the number of cycles.

Laminate structures of multiple layers formed using ALD can also besubsequently processed to mix the individual layers together. Forexample, a zinc-tin oxide film laminate structure can be annealed to mixa plurality of different layers together, thus forming an alloy or asolid-solution mixture of layer chemistries. By forming a laminatestructure using ALD and subsequently mixing the layers, the chemistry ofthe resulting structure is precisely controlled. Because the laminate ismade up of self-limiting monolayers over a known surface area, thenumber of molecules from each individual layer are known to a highdegree of accuracy. Chemistry can be controlled by adding or subtractingone or more layers in the laminate.

In an embodiment, multiple alternating monolayers are laminated abovethe deposition substrate before processing.

Referring to FIG. 5, a substrate 510 is located inside a reactionchamber 520 of the ALD tool 500. Also located within the reactionchamber 520 is a heating element 530 that is thermally coupled tosubstrate 510 to control the substrate temperature. A gas-distributionfixture 540 introduces precursor gases to the substrate 510. Eachprecursor gas originates from individual gas sources 551 through 554whose flow is controlled by mass-flow controllers 556 through 559,respectively. The gas sources 551 through 554 provide a precursor gaseither by storing the precursor as a gas or by providing a location andapparatus for evaporating a solid or liquid material to form theselected precursor gas.

Also included in the ALD system 500 are purging gas sources 561 and 562,each of which is coupled to mass-flow controllers 566 and 567,respectively. The gas sources 551 through 554 and the purging gassources 561 through 562 are coupled by their associated mass-flowcontrollers to a common gas line or conduit 570 that is coupled to thegas-distribution fixture 540 inside the reaction chamber 520. The gasconduit 570 is also coupled to vacuum pump or exhaust pump 581 by amass-flow controller 586 to remove excess precursor gases, purginggases, and by-product gases at the end of a purging sequence from thegas conduit 570.

A vacuum pump or exhaust pump 582 is coupled by mass-flow controller 587to remove excess precursor gases, purging gases, and by-product gases atthe end of a purging sequence from the reaction chamber 520. Forconvenience, control displays, mounting apparatus, temperature sensingdevices, substrate maneuvering apparatus, and sufficient electricalconnections as are known to those skilled in the art are not shown inFIG. 5. Although ALD system 500 is illustrated as an example, other ALDsystems may be used.

Although a number of examples of precursors, oxidizers, and processconditions are listed above for ALD forming TCO and TSO structures, theembodiments are not so limited. One of ordinary skill in the art, havingthe benefit of the present disclosure will recognize that otherchemistries and process conditions that form ALD forming TCO and TSOstructures can be used.

FIG. 6 illustrates an electronic device 600 that includes tin-zinc oxidefilms formed using monolayer deposition methods such as ALD as describedabove. The electronic device 600 includes a first component 620 thatbenefits from tin-zinc oxide films. Examples of first component 620include dynamic random-access memory arrays. In an embodiment, the firstcomponent 620 is a processor that includes flash memory arrays that areused for booting up the processor. In these examples, device operationis improved with the thickness of the TCO structures.

In an embodiment, the device 600 further includes a power source 630.The power source 630 is electrically connected to the first devicecomponent 620 using interconnecting circuitry 640. In an embodiment, theinterconnecting circuitry 640 includes tin-zinc oxide films formed frommonolayers using ALD methods described above. In addition to depositingmaterial as described above, techniques such as lithography with masksand/or etching etc. can be used to pattern conducting circuitry.

In an embodiment, the device 600 further includes a second devicecomponent 610. The second component is electrically connected to thefirst component 620 using interconnecting circuitry 642. Likewise, inone embodiment, the interconnecting circuitry 642 includes tin-zincoxide films that are formed using methods described above. Examples ofsecond device components 610 include signal amplifiers, flash memory,logic circuitry, or other microprocessing circuits, etc. Aside frominterconnecting circuitry, in an embodiment, the first device component620 and/or the second device component 610 includes tin-zinc TCO filmsformed as from monolayer precursors using methods described above.

FIG. 7 shows one specific example of a computer system includingtin-zinc oxide films formed as described above. The computer system 700contains a processor 710 and a memory system 712 housed in a computerunit 715. The computer system 700 is but one example of an electronicsystem containing another electronic system. In an embodiment, thecomputer system 700 contains an I/O circuit 720 that is coupled to theprocessor 710 and the memory system 712. In an embodiment, the computersystem 700 contains user interface components that are coupled to theI/O circuit 720. In an embodiment, a tin-zinc oxide film is coupled toone of a plurality of I/O pads or pins 730 of the I/O circuit 720. TheI/O circuit 720 can then be coupled to at least one of a monitor 740, aprinter 750, a bulk storage device 760, a keyboard 770, and a pointingdevice 780. It will be appreciated that other components are oftenassociated with the computer system 700 such as modems, device drivercards, additional storage devices, etc. It will further be appreciatedthat the processor 710, the memory system 712, the I/O circuit 720, andpartially isolated structures or data storage devices of computer system700 can be incorporated on a single integrated circuit. Such singlepackage processing units may reduce the communication time between theprocessor 710 and the memory system 700.

This Detailed Description refers to the accompanying drawings that show,by way of illustration, specific aspects and embodiments in which thepresent disclosure may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice thedisclosed embodiments. Other embodiments may be used and structural,logical, and electrical changes may be made without departing from thescope of the present disclosure. The various embodiments are notnecessarily mutually exclusive, as some embodiments can be combined withone or more other embodiments to form new embodiments.

The Detailed Description is, therefore, not to be taken in a limitingsense, and the scope of this disclosure is defined only by the appendedclaims, along with the full scope of equivalents to which such claimsare entitled.

The terms “wafer” and “substrate” used in the description include anystructure having an exposed surface with which to form an electronicdevice or device component such as a component of an integrated circuit(IC). The term substrate is understood to include semiconductor wafers.The term substrate is also used to refer to semiconductor structuresduring processing and may include other layers such assilicon-on-insulator (SOI), etc. that have been fabricated thereupon.Both wafer and substrate include doped and undoped semiconductors,epitaxial semiconductor layers supported by a base semiconductor orinsulator, as well as other semiconductor structures well known to oneskilled in the art.

The term conductor is understood to include semiconductors and the terminsulator or dielectric is defined to include any material that is lesselectrically conductive than the materials referred to as conductors.

The term transparent is defined as a property of a material thattransmits a substantial portion of incident electromagnetic energy in agiven frequency range. Examples of electromagnetic energy ranges includevisible frequency light, infrared, ultraviolet, etc. or combinations offrequency ranges.

The term monolayer is defined as a material layer that is substantiallyone molecule thick. In some embodiments, one molecule includes one atom,while other molecules are comprised of several atoms. The term monolayeris further defined to be substantially uniform in thickness, althoughslight variations of between approximately zero to two monolayersresults in an average of a single monolayer as used in descriptionbelow.

The term “horizontal” as used in this application is defined as a planeparallel to the conventional plane or surface of a wafer or substrate,regardless of the orientation of the wafer or substrate. The term“vertical” refers to a direction perpendicular to the horizontal asdefined above. Prepositions, such as “on,” “side” (as in “sidewall”),“higher,” “lower,” “over,” and “under” are defined with respect to theconventional plane or surface being on the top surface of the wafer orsubstrate, regardless of the orientation of the wafer or substrate.

The Abstract is provided to comply with 37 C.F.R. § 1.72(b), requiringan abstract that will allow the reader to quickly ascertain the natureof the technical disclosure. It is submitted with the understanding thatit will not be used to interpret or limit the scope or meaning of theclaims. In addition, in the foregoing Detailed Description, variousfeatures may be grouped together to streamline the disclosure. Thismethod of disclosure is not to be interpreted as reflecting an intentionthat the claimed embodiments require more features than are expresslyrecited in each claim. Rather, as the following claims reflect,inventive subject matter may lie in less than all features of a singledisclosed embodiment. Thus the following claims are hereby incorporatedinto the Detailed Description, with each claim standing on its own as aseparate embodiment.

1. A process comprising: forming a plurality of chemically adheredmonolayers on a substrate; and processing the plurality of chemicallyadhered monolayers to form a zinc-tin compound containing a transparentconductive oxide (TCO) structure.
 2. The process of claim 1, whereinprocessing includes alloying the plurality of chemically adheredmonolayers on the substrate.
 3. The process of claim 1, wherein the TCOstructure is formed epitaxially upon a semiconductor active section ofthe substrate.
 4. The process of claim 1, wherein the TCO structure isformed upon a dielectric section of the substrate.
 5. The process ofclaim 1, wherein forming the plurality of chemically adhered monolayersincludes disposing an organo-zinc monolayer against an organo-tinmonolayer.
 6. The process of claim 1, wherein forming the plurality ofchemically adhered monolayers includes disposing an zinc halidemonolayer against a tin halide monolayer.
 7. The process of claim 1,wherein processing the plurality of chemically adhered monolayersincludes forming a TCO film that abuts an electronic device disposed atthe substrate.
 8. The process of claim 1, wherein processing theplurality of chemically adhered monolayers includes forming a TCO filmas a channel layer in a field-effect transistor.
 9. The process of claim1, wherein processing the plurality of chemically adhered monolayersincludes: forming a TCO film that abuts an electronic device disposed atthe substrate; and forming a TCO film as a channel layer in afield-effect transistor.
 10. A process comprising: forming one of azinc-containing first monolayer or a tin-containing first monolayer on asubstrate that is disposed in a tool; purging the tool; forming theother of the zinc-containing monolayer or the tin-containing monolayeron the first monolayer to form a plurality of chemically adheredmonolayers; and processing the plurality of chemically adheredmonolayers to form a transparent zinc-tin oxide structure therefrom. 11.The process of claim 10, wherein at least one of the zinc-containingmonolayer is a zinc halide monolayer or the tin-containing monolayer isa tin halide monolayer.
 12. The process of claim 10, wherein at leastone of the zinc-containing monolayer is an organo-zinc monolayer or thetin-containing monolayer is an organo-tin monolayer.
 13. The process ofclaim 10, further including abutting the transparent zinc-tin oxidestructure against an electronic device disposed at the substrate. 14.The process of claim 10, further including forming a gate stack abovethe transparent zinc-tin oxide structure, the process including: forminga gate dielectric layer above and on the transparent zinc-tin oxidestructure; and forming a control gate film against the gate dielectriclayer.
 15. The process of claim 10, further including: abutting thetransparent zinc-tin oxide structure against an electronic device; andforming a gate stack above the transparent zinc-tin oxide structure, thegate stack forming process including: forming a gate dielectric layerabove and on the transparent zinc-tin oxide structure; and forming acontrol gate film against the gate dielectric layer.
 16. The process ofclaim 10, wherein processing the plurality of chemically adheredmonolayers to form a transparent zinc-tin oxide structure includesforming multiple alternating layers of zinc- and tin-containingmonolayers.
 17. The process of claim 10, wherein processing theplurality of chemically adhered monolayers to form a transparentzinc-tin oxide structure includes heating the monolayers in the presenceof an oxidizer.
 18. An electrical device, comprising: a first devicecomponent; a second device component coupled to the first devicecomponent; and a transparent zinc-tin oxide structure disposed in one ofthe first and second device component, wherein the transparent zinc-tinoxide structure is formed by a method including: atomic layer depositinga first monolayer; atomic layer depositing at a second monolayer; andprocessing the monolayers to form a transparent zinc-tin oxide chemicalmixture of the monolayers.
 19. The electrical device of claim 18,wherein the first device component includes a field-effect transistorcomponent.
 20. The electrical device of claim 18, wherein the seconddevice component includes a field-effect transistor component.
 21. Theelectrical device of claim 18, wherein the transparent zinc-tin oxide ofthe chemical mixture is disposed as a channel layer in a field effecttransistor.
 22. The electrical device of claim 18, wherein the chemicalmixture has a thickness in a range from about 3 {acute over (Å)} toabout 300 {acute over (Å)}.